In an injected molded article, a live hinge is a single flexible part molded integrally with two components, so that pivoting can occur between the components along the live hinge. A live hinge can be an elegant and relatively simple way to provide a hinged article. When molding an article with a live hinge, it is common to exercise the hinge before it cools after the molding process, thereby providing flexibility and free movement of the live hinge.
It is known to provide live hinges between a vessel and a lid of an injected molded articles, so that the lid will seal the vessel and thereby provide a closed container. Exercising the hinge shortly after injection in order to close the lid can be particularly desirable for such closed containers, in order to reduce problems that can arise from non-uniform shrinkage of the injected materials during cooling, which can lead to an improper fit between the lid and vessel. Closing the lid of the molded container can allow the lid and vessel to cool and shrink together and thereby form a proper fit.
Devices for exercising live hinges of molded articles while in the mold are known. U.S. Pat. No. 4,351,630 to Hayberg, issued Jul. 20, 1982, describes various devices for exercising a live hinge, the contents which is incorporated herein by reference. One such device is described by way of the background in Hayberg. This device uses compressed air and pistons to move pins that initially push the lid away from the molding surface to exercise the live hinge. However, such air pistons are not always effective in exercising or closing smaller lids with smaller surface areas.
The use of such an in-mold lid closing device obviates many of the costs and challenges associated with the alternative of providing a post-molding system for re-orienting the molded articles, as required, and subsequently effecting a closing of the lids. For example, where the molded article is configured to provide the function of at least a portion of an aseptic container the additional handling and manipulation steps effected by the post-molding system may undesirably increase the risk of contaminating the molded article.
Hayberg also discloses a device for exercising a live hinge and closing a lid while in the mold, by the action of a finger engaging with the lid. There are however, several disadvantages with Hayberg wherein the lid closing device, along with a dedicated actuator therefore, is arranged at the periphery of the mold. For example, the device cannot be readily used with an injection mold that includes a laterally actuated side core (side cores are known for use in molding features on the molded article that are at a substantial angle with respect to the draw of the mold, such as an integrally formed lid that is formed at an acute angle to a base portion, or a live hinge that is configured between the sides of the molded article) that may interfere with the proper transit of the lid closing device that must enter from the periphery of the mold. In addition, the device also has a large physical space requirement that may limit the productivity of the tool (i.e. lower mold cavitation). Furthermore, the device introduces additional cost and control complexities associated with the need for a dedicated actuator and for sequence coordination between the steps of operating the device with those of the mold. Additionally, Hayberg discloses how to exercise live hinges where the hinge is located on the periphery of the vessel (or other base portion), but does not disclose formation of articles where the live hinge is located elsewhere on the vessel.